title: In silico and in vitro metabolism studies support identification of designer drugs in human urine by liquid chromatography/quadrupole-time-of-flight mass spectrometry.
abstract: Human phase I metabolism of four designer drugs, 2-desoxypipradrol (2-DPMP), 3,4-dimethylmethcathinone (3,4-DMMC), α-pyrrolidinovalerophenone (α-PVP), and methiopropamine (MPA), was studied using in silico and in vitro metabolite prediction. The metabolites were identified in drug abusers’ urine samples using liquid chromatography/quadrupole-time-of-flight mass spectrometry (LC/Q-TOF/MS). The aim of the study was to evaluate the ability of the in silico and in vitro methods to generate the main urinary metabolites found in vivo. Meteor 14.0.0 software (Lhasa Limited) was used for in silico metabolite prediction, and in vitro metabolites were produced in human liver microsomes (HLMs). 2-DPMP was metabolized by hydroxylation, dehydrogenation, and oxidation, resulting in six phase I metabolites. Six metabolites were identified for 3,4-DMMC formed via N-demethylation, reduction, hydroxylation, and oxidation reactions. α-PVP was found to undergo reduction, hydroxylation, dehydrogenation, and oxidation reactions, as well as degradation of the pyrrolidine ring, and seven phase I metabolites were identified. For MPA, the nor-MPA metabolite was detected. Meteor software predicted the main human urinary phase I metabolites of 3,4-DMMC, α-PVP, and MPA and two of the four main metabolites of 2-DPMP. It assisted in the identification of the previously unreported metabolic reactions for α-PVP. Eight of the 12 most abundant in vivo phase I metabolites were detected in the in vitro HLM experiments. In vitro tests serve as material for exploitation of in silico data when an authentic urine sample is not available. In silico and in vitro designer drug metabolism studies with LC/Q-TOF/MS produced sufficient metabolic information to support identification of the parent compound in vivo.
authors.affiliation: Department of Forensic Medicine, Hjelt Institute, University of Helsinki, P.O. Box 40, 00014 Helsinki, Finland. elli.tyrkko@helsinki.fi
authors.forename: Elli
authors.initials: E
authors.lastname: Tyrkkö
authors.forename: Anna
authors.initials: A
authors.lastname: Pelander
authors.forename: Raimo A
authors.initials: RA
authors.lastname: Ketola
authors.forename: Ilkka
authors.initials: I
authors.lastname: Ojanperä
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D003198:Computer Simulation; D015198:Designer Drugs / Q000032:analysis / Q000378:metabolism*; D015195:Drug Design; D006801:Humans; D008861:Microsomes / Q000378:metabolism*; D008954:Models, Biological; D012984:Software; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D015813:Substance Abuse Detection / Q000379:methods*; D016482:Urinalysis / Q000379:methods*
chemical_list: D015198:Designer Drugs